Tuesday, 28 October 2014

Pretty Beach Rocks

On the NSW South Coast, just south of Kioloa, there is a little place tucked away in the northern reaches of the Murramarang National Park called Pretty Beach. And it is. One of the features of the place that I love is the sculpturing of the rocks along the northern headland. The sandstone there seems particularly prone to honeycomb weathering, and here it takes on some intriguing forms that are really cool. So you can interpret this blog post’s title as Pretty Beach rocks, pretty beach rocks, or Pretty Beach rocks!

I’ve camped in and explored the area several times in the past, especially when my son was about 8 years old, and have some very fond memories. But perhaps another large part of the reason I love the area is that it is within the Sydney Basin, albeit towards the southern edge, so has the typical geology and floral ecology of the sandstone landscapes that I grew up with as a kid in northern Sydney.

James in his speed boat at Pretty Beach, October 2004.
James at Pretty Beach, October 2004.

The Sydney Basin stretches from South Durras in the south to Newcastle in the north, reaches west to Lithgow, Mudgee and north-west of Muswellbrook, and east to the edge of the continental shelf some 30 odd kilometres offshore. The total land area of the Basin is about 44,000 square kilometres (plus a further 5,000 square kilometres offshore). The bit I’m referring to in this blog post occupies about 300 square metres, just 0.0000006% or 6 billionths of the Basin.

The Sydney Basin is defined geologically by the sedimentary sequences of Permian and Triassic sandstones, coal seams and shales that were laid down some 290-200 million years ago. The earlier Permian Sandstones derive mainly from marine sediments, the later deposits from freshwater alluvial fan and fluvial deposits. Uplifting of the area during the middle Triassic about 230 million years ago raised the whole basin, the eroded outer edges of which now manifest as impressive landforms such as the massive sandstone cliffs and escarpments, hidden valleys, and plateaux of places like the Blue Mountains, Capertee Valley, Morton National Park etc.

At Pretty Beach, the sandstone is from the early Permian and is derived from marine sediments, so fossil shells are often seen in the rocks. I recall going on an excursion to Kioloa back in 1979 during my first year of university, on which we made a brief visit to some fossil beds at Merry Beach, just around the headland from Pretty Beach. 

The strata in the sandstone are evident in the cliff faces. 

Both the rock platforms and the massive fallen boulders are subject to honeycomb weathering.

Rock platform at Pretty Beach showing honeycomb weathering of the soft sandstone.

Fossilised scallop shells exposed in a slab of Permian sandstone fallen from higher up the cliff.

The next set of photos just gives an impression of the diversity of forms the honeycomb weathering can take. 

And weirdly, for some reason pitting is sometimes concentrated along cracks in the sandstone.

And the play of light made depressions look like raised nodules.

And probably best of all are the miniature 'volcanic' landscapes - I've no idea how or why these develop quite like this.

Eventually the sandstone is eroded to small grains of sand, producing the stunning golden beaches for which the Sydney region is famous. 

And being a birdo, I can't possibly leave this post without including at least one bird!

Eastern Reef Egret (or Pacific Reef Heron) flying past O'Hara Island at Pretty Beach, NSW.

It's been a few years now since I last visited Pretty Beach - time to go again, I think. 

For anyone interested, there is some good information, particularly about the geological and geomorphological aspects of the Sydney Basin, but also a little about the ecology, at these sites:


Sunday, 12 October 2014

Buddigower Banding - an unsprung Spring?

The weather was unseasonably warm and the bush very dry. The last time I had been out there banding, exactly four years prior, the place had been awash with wildflowers and everything seemed fresh and vibrant. This time it all seemed a little tired.

Buddigower Nature Reserve is in central New South Wales, just 7 km further along a dirt road from the Charcoal Tank Nature Reserve (12 km south of West Wyalong) where we have a regular bird banding site. We generally only get to Buddigower about every three years, and this time the gap had been four. Apart from the core group of eight banders, there were also five COG members (COG = Canberra Ornithologists Group) along for the ride on this Labour Day long weekend (3-6 October).

I’d been in Melbourne for work on the Friday so couldn’t get out to Buddigower until later on the Saturday afternoon. But this did mean we were travelling in daylight and along the way we stopped for a couple of reptiles on the road to ensure they didn't become road-kill.

A Shingleback Lizard Tiliqua rugosa (Scincidae)
was persuaded to remove itself from the middle of the road.

And a beautiful Sand Monitor (or Gould's Goanna) Varanus gouldii (Varanidae) welcomed us to Buddigower

while always keeping a close eye on us. 

When we arrived at Buddigower, Karen and I set to to get a few nets up before dusk, in the same area we had banded those four years previously, then went about the business of setting up camp. It seems Mark and his crew, who had set up on the Friday afternoon, hadn’t done so well, with less than 20 birds banded for the day.

The dryness may well be the first sign of the predicted el Niño cycle. Whatever the case, there wasn’t much flowering; certainly not the main woodland eucalypt species, nor the widespread understorey of cassinia bushes. But there were several acacias still in flower. And a few isolated cassia bushes, as well as a scattering of Calytrix, Thysanotus, and some everlastings, added splashes of colour (mainly yellow) to the otherwise fairly muted landscape.

Currawang Acacia doratoxylon (Fabaceae-Mimosaceae)

Streaked Wattle Acacia lineata (Fabaceae-Mimosaceae)

A cassia (probably Cassia nemophila) (Fabaceae-Caesalpiniaceae). In the early morning the surrounding bushland was redolent with the scent from these bushes, smelling like freshly prepared garam masala!

Common Fringe-myrtle Calytrix tetragona (Myrtaceae)

Twining Fringe-lily Thysanotus patersonii (Anthericaceae)

A 'Yellow Buttons' everlasting (Chrysocephalum sp. either apiculatum or semipapposum)

There were certainly birds about. They were quite vocal, and fairly active, but mostly they kept to the canopy so we had little success at the nets. At our site, Karen and I managed just 23 birds for the weekend: 7 White-browed Babblers, several Eastern Yellow Robins (including a presumed family party of mum, dad, and a stripe-headed juvenile in the first net on the first round), 3 White-eared Honeyeaters, a couple of Red-capped Robins, a Variegated Fairy-wren, a very obstreperous kookaburra (with its mate egging it on from the sidelines), a trio of Grey Fantails and a Willie Wagtail. The juvenile robin, as well as a few birds with brood patches, were the only signs that some birds at least were breeding. The Rufous Whistlers, Weebills, Inland Thornbills, Western Gerygones, Jacky Winters, Grey Shrike Thrush and Mistletoebirds were constant and welcome vocal companions but all stayed resolutely away from the nets.

White-browed Babbler Pomatostomus superciliosus (Pomatostomidae)
one of the seven caught was a re-trap from the 2010 trip.

Male Red-capped Robin Petroica goodenovii (Petroicidae)

This little Inland Thornbill Acanthiza apicalis (Acanthizidae) came to investigate why the Red-capped Robin was making such a fuss while he was being photographed immediately prior to release.

The middle of the day was hot. 36 degrees hot! More than the predicted 32, which would have been bad enough, and well above the long-term average for October (about 24ºC). The birds quietened down, but the mad-dog non-Englishman (me, in this case) continued his vain pursuit of them - in vain.

The insects, however, seemed to be enjoying the conditions. Several butterflies (Meadow Argus, Australian Painted Lady, Caper White, and a tiny grass blue) were around in small numbers. One Meadow Argus had taken a liking to, indeed laid claim to, a three square metre patch of track and was flushed each and every time I passed to check the net. Grasshoppers of several species gave me some great opportunities to play with my new macro lens, as did several robber flies, and the occasional dragonfly hummed by (possibly an emerald or emperor?) or perched on exposed twigs (Wandering Percher).

Australian Plague Locust Chortoicetes terminifera - brown form.

Australian Plague Locust Chortoicetes terminifera - green form.

Grasshopper 'type B' - red & grey form.

Grasshopper 'type B' - orange form.

The 'type B' grasshoppers would wave their front legs about
in what looked like some kind of semaphoric signalling 

and had gnarly 'old man' faces.

Robber fly 'type A' - male

Robber fly 'type A' - female.
The dense cluster of bristles in front of the face is called a mystax;
it helps to protect the fly against the struggles of any incalcitrant insect prey.

At first I thought this was a weird-looking robber fly (Asilidae) but on looking it up determined that it is in fact a species of Apiocera, from the family Apioceridae - closely related to Asilidae but one I've never come across before. Woo-hoo!

With evening, the temperature dropped slightly and the spiders came out to prowl, their eye-shine, reflecting back from the ground in front of our head-lamps, as bright as the stars above. More scope for a bit of macro experimentation. While I focussed on the larger spiders for photography, it was evident there were very many young spiders about, clearly following a major recent hatching event.

A wolf spider on the prowl.

Ain't she beautiful!

Another wolf spider hiding in its burrow - this one has very dark chelicerae compared to the first one.

I managed to induce it out of its burrow by scratching the ground with a small twig...

and got a great face on photo before it scuttled back down its hole. 

Another night-time discovery provided, for me, the highlight of the trip. There had been a Spotted Nightjar calling sporadically the previous two evenings, but on Sunday night a brief bout of spotlighting by some of the group located a nightjar nesting on the ground not far from camp (thanks Kathy), while its mate continued to call in its distinctive and eerie way as it swept over the tree-tops or the more distant paddocks. I’d just settled down for a well needed sleep when alerted to the find, but I threw off the sheet and was pulling on jeans in an instant for this opportunity.

Spotted Nightjar Eurostopodus argus (Caprimulgidae) on its nest at night.

Spotted Nightjars lay a single, pale green, speckled egg,
the 'nest' being a simple scrape in the leaf litter.

Next morning, the Spotted Nightjar's camouflage in the dappled sunlight was exquisite. Just as well I knew exactly where the nest was.

Spotted Nightjar Eurostopodus argus (Caprimulgidae) on its nest - what a great bird

So while the bird banding could have been better, and spring breeding isn't perhaps in fullest swing, the trip was undeniably a success.